My mom is showing signs of what might be dementia. What should I do?

I noticed my mom's mood changing and her not being as clean with her animals as she had been before. She doesn't want to go to the Neurologist so I gave her the clock test. I asked her if she could just draw a clock for me and it took forever before she would at least try. I asked her if she could draw a picture of a clock. She only wrote the word clock. I told her just try to draw just a picture and no words but she could not. I asked if she might draw a triangle but only wrote the word Triangle. I hate to think my mom has dementia but it's really scary just letting it go. I want to help her as much as I can but she is very set in her ways. If anyone saw this kind of behavior or could help I'd really appreciate it.